Night vision devices are commonly used by military personnel for conducting operations in low light or night conditions. The night vision devices utilized by the military typically include image intensifier tubes and associated optics that convert infrared and near infrared light into viewable images. A common night vision device currently being used in the U.S. Army is the PVS7 night vision goggle, manufactured by ITT Corporation in Roanoke, Va.
Assemblies for mounting night vision devices to a helmet are well known in the art. These mounting assemblies allow a user's hands to remain free while viewing a scene through the night vision device. Prior art mounting assemblies typically include one or more of the following features: positional adjustment of the night vision device between a use and stowed position; tilt angle adjustment of the night vision device relative to the user's eyes; focal adjustment of the location of the night vision device relative to the user's eyes; and automatic shutdown of the night vision device when not in the use position.
An example of a prior art mounting assembly for night vision devices can be seen in U.S. Pat. No. 5,506,730 to Morely et al. (hereinafter "Morely"). Morely discloses a flip-up helmet mount for a night vision goggle that attempts to provide all of the features identified above. However, the device disclosed by Morely is believed to be deficient in its operational aspects because, among other reasons, the flip-up helmet mount is not designed for one-handed operation. More particularly, the tilt adjustment means disclosed by Morely requires a user to loosen a locking knob with one hand, while at the same time repositioning the night vision device with the other hand. Obviously, given the conditions under which night vision devices are typically used, it is undesirable and potentially unsafe for adjustment of the night vision device to occupy both hands of the operator. If both hands of the operator are required to adjust the night vision device, then the operator will be unable to continue carrying a weapon or other equipment in one of his hands. It can certainly be appreciated that having to put down one's weapon in order to adjust the night vision device may expose the operator of the device to certain unnecessary risks.
The flip-up helmet mount disclosed in Morely is also believed to be deficient in its operational aspects because of the automatic shutdown assembly's susceptibility to jamming. The automatic shutdown assembly disclosed in Morely includes a magnet housing having an S-shape or question-mark shape. Commercial embodiments of the Morely helmet mount include a long (e.g. 1 inch in length), narrow (e.g. 1/8 inch in diameter) cylindrical bar magnet movably received within the S-shaped cavity. This combination of an S-shaped cavity and a relatively long, narrow bar magnet results in an automatic shutdown assembly with questionable reliability. Specifically, the long, narrow bar magnet can easily become askew within the S-shaped cavity as the magnet moves within the cavity. When the magnet becomes askew within the cavity, the automatic shutdown assembly becomes jammed and the night vision device does not automatically turn off when rotated into the stowed position. This is obviously undesirable since the phosphor yellow/green light emitted from the night vision device would then be visible to possibly hostile personnel in front of the operator.
There are additional aspects of the flip-up helmet mount disclosed in Morely that are believed to be inadequate given the conditions in which these devices are typically used. For example, Morely discloses a rib that is receivable into one of two grooves to retain the night vision device in either the use or stowed position. However, a significant amount of noise is produced by this rib and groove combination when the rib engages the groove. Obviously, excessive noise can draw unwanted attention to the operator of the night vision device.
Additionally, the focal adjustment assembly disclosed in Morely requires the operator of the night vision device to apply force inwardly to a pair of release buttons in order to adjust the location of the night vision device relative to his eyes. It is believed that this requires a rather awkward movement of the hand or hands of the operator that makes focal adjustment relatively difficult.
These and other problems exist with the flip-up helmet mounts for night vision devices disclosed in the prior art. Consequently, a need exists for an improved flip-up helmet mount.